This is a pretty great game, it is a very polished experience and its presentation is fantastic! I would say that the gameplay needs a bit more of an explanation as it definitely took me a bit to figure out what I was supposed to and then how I was dying (extended legs and hat hitting objects) and then got really confused when you pass the extended bits through small gaps as I had no idea the piston arm didn't have collision either, also the boxes should perhaps be shaded to make them appear pushed back a bit, they look like they are directly in the foreground and are obstacles you'll collide with.
With that said, once you get a handle on the controls and gameplay, it is super fun and clever and I love the style and theme you went with, a piston-powered jousting knight, just fantastic! Great job!